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Electromyography in ergonomics
Published in Kumar Shrawan, Mital Anil, Electromyography in Ergonomics, 2017
Jonsson (1970) reported the functions of individual muscles in the lumbar region of the erectores spinae, more specifically the multifidi, longissimus, and iliocostalis at different lumbar vertebral levels. He inserted wire electrodes guided by TV fluoroscopy to place them in the pick-up area accurately. He also used a common gain for all channels for studying static contractions in prone, standing and sitting postures. He graded all EMG recordings on a three-point scale: 0 = no activity, 1 = slight activity (individual action potentials were perceptible and the baseline was not obscured), and 2 = marked activity (the base line was obscured by the action potentials). He only measured the mean activity. Using this simple scoring system, Jonsson (1970) was able to demonstrate that there was no significant difference between muscle loads to left and right sides of the body in symmetrical postures. Furthermore, he reported no difference between the medial or lateral placement of electrodes in the longissimus. He also concluded that there were differences in function between the multifidi, longissimus, and iliocostalis muscles even at the same level; sometimes differences in function occur between different vertebral levels even in the lumbar region.
Modeling and simulation of tissue load in the human spine
Published in Youlian Hong, Roger Bartlett, Routledge Handbook of Biomechanics and Human Movement Science, 2008
N. Arjmand, B. Bazrgari, A. Shirazi-Adl
As the trunk flexes forward from upright posture, initially both active and passive components of forces in global extensor muscles increase with the formers reaching their peak values at about 45° (Figure 3.3). Thereafter, up to the trunk flexion of about 95°, active forces in thoracic extensor muscles diminish despite the continuous increase in net external moment reaching its maximum of 118 Nm. On the contrary, passive muscle forces as well as passive ligamentous moment increase throughout the movement to peak lumbar flexion (Figures 3.3 and 3.5). The progressive relief in activity of global back muscles is due, therefore, to higher passive contribution of muscles and ligamentous spine as the lumbar rotation increases. As the trunk flexion exceeds about 95° (at about 3.3 sec), lumbar rotation (Figure 3.3) and consequently both passive muscle force and moment resistance of the ligamentous spine, remain nearly unchanged, while the activity of back muscles continues to drop. In this case, the reduction in net external moment due to the decrease in the effective lever arm of the trunk centre of mass (COM) is the primary cause in progressive decrease in back muscle activities. Global longissimus [LGPT] and iliocostalis [ICPT] become completely silent at trunk flexion angles of about 114° and 95°, respectively.
Functional Anatomy and Biomechanics
Published in Emeric Arus, Biomechanics of Human Motion, 2017
Musculus erector spinae represents three different muscles, musculus ilio- costalis, longissimus, and spinalis. These muscles adhere to three distinctive regions of the vertebral column. They occupy the costovertebral grooves excepting the iliocostalis muscle. They have a commune muscular mass on the sacrolumbar portion of the sacrum which is connected to fascia toraco- lumbaris. Also this commune muscular mass is connected to the spinous processes of the last lumbar vertebrae, the median ridge of the sacral bone, the posterior part of the sacrum, and on the posterosuperior iliac spine.
Influence of a passive back support exoskeleton on simulated patient bed bathing: results of an exploratory study
Published in Ergonomics, 2023
Pauline Maurice, Félix Cuny-Enault, Serena Ivaldi
Table 2 summarises the results of the ANOVA conducted on the EMG data for each step of the bed bathing task separately. Only the effect of the intervention factor is reported, for the sake of readability and because it is the main focus of the study.1 The ANOVA revealed a significant effect of intervention on muscle activity of several of the erector spinae muscles (LL left, LL right, LT left and/or IL left depending on the step), but only during the second half of the task starting from when the manikin is turned on its side. Left erector spinae muscles were affected at different levels (longissimus lumborum, longissimus thoracis and iliocostalis lumborum), while on the right side only the longissimus lumborum was affected. In all cases, the muscle activity was reduced when using the exoskeleton compared to without it, by 12–17% in average for LL left, 13–19% for IL left, 8% for LT left, and 32–44% for LL right. No significant effect of the exoskeleton was detected on any other muscle, except on the right BF in the first step of the task. Effect sizes are however small for all muscles and steps ().
Obesity effects on muscular activity during lifting and lowering tasks
Published in International Journal of Occupational Safety and Ergonomics, 2021
Ana Colim, Pedro Arezes, Paulo Flores, Pedro Ribeiro Rocha Monteiro, Inês Mesquita, Ana Cristina Braga
Bilateral muscle activity was assessed for selected sets of muscles: right and left erector spinae (iliocostalis) at L2 (RI, LI); right and left erector spinae (longissimus) at L1 (RL, LL); right and left deltoideus anterior (RD, LD) (Figure 2). These muscles are placed in body areas that do not present high fat mass accumulation, which could compromise the EMG data acquisition. Additionally, the selection of these muscles was based on their functionality during the VHT performance, namely, the deltoideus anterior acts in glenohumeral joint mobilization and the erector spinae muscles are responsible for trunk extension and stabilization during the VHT performance [30,42]. Evaluation of the percentage of maximum contraction during each task (MCT%) was considered for each trial, segregating lifting and lowering tasks, and for each muscle.
Effects of prolonged microscopic work on neck and back strain amongst male ENT clinicians and the benefits of a prototype postural support chair
Published in International Journal of Occupational Safety and Ergonomics, 2019
Ananth Vijendren, Gavin Devereux, Bruno Kenway, Kathy Duffield, Vincent Van Rompaey, Paul van de Heyning, Matthew Yung
A 4-channel BIOPAC MP45 data acquisition system (BIOPAC Systems, USA) collected sEMG signals for measurement of the muscular activity (signal amplitude, μV). The sEMG channels were amplified at a fixed gain of 1000 by the bio-amplifier, and were bandpass filtered between 5 and 1000 Hz. Bipolar surface electrodes were placed on the right-hand and left-hand sides of the neck and back as follows: the neck electrodes were placed at the midline from the acromion process to the spine of C7 vertebra with the electrodes 2 cm distant from each other. These electrodes measured the muscle activity of the upper branches of the trapezius descendens muscles [6,7]. The back electrodes were placed 2 cm distant from each other at two fingers width laterally from the spinous processes of L1 to measure the longissimus branches of the erector spinae muscles [6].